1. Field
The present inventive concept relates to a dual inverter system to drive a motor and a method of controlling the same.
2. Description of the Related Art
In general, an inverter converts a DC voltage into an AC voltage.
The inverter is one of power converters and is widely used in electric apparatus including home appliances, such as an air conditioner, a refrigerator, a washing machine, or a cooking machine.
An inverter driver in an electric home appliance drives a load, such as a motor, by switching a plurality of power devices in an inverter circuit based on a gate signal output from a controller.
The inverter is classified into a 2-phase electrical conduction type and a 3-phase electrical conduction type according to how many power devices are electrically conducted when a load is driven. That is, if two power devices are electrically conducted, the inverter is called a 2-phase electrical conduction type inverter, and if three power devices are electrically conducted, the inverter is called a 3-phase electrical conduction type inverter.
The power devices provided in the inverter are divided into a high side group and a low side group, and a gate signal applied to the power devices is a pulse width modulation (PWM) signal.
After the PWM signal is applied to the power devices provided in the inverter, PWM is generated based on a current sensed from an output node of the inverter. Here, a current transducer (CT) or a Hall effect sensor is used as a current sensor to sense the current of the output node. In this case, the inverter driver may have an increased cost, which is problematic.
The current of the output node of the inverter may also be sensed using a resistor and a differential amplifier. Since the differential amplifier is relatively expensive, the manufacturing cost of the inverter driver may increase.
In addition, in a case where the inverter is employed to a washing machine, in order to cope with the tendency toward large size and high efficiency washing machines, it is necessary to increase a DC terminal voltage of the inverter. However, there is a limit in increasing the DC terminal voltage because single-phase power for home use is simply rectified to be used.
Therefore, in order to increase the DC terminal voltage of the inverter, a separate power boosting converter should be used. In this case, the price of a product may increase and an energy loss may increase during power conversion.